1. Field of the Invention
The present invention relates to a communication control apparatus and a control method thereof, a communication apparatus and a control method thereof, a wireless communication system, a program, and a storage medium.
2. Description of the Related Art
Technology that aims to configure plural connection links through relay transmission and carry out wireless transmission with a remote communication terminal is known (Japanese Patent Laid-Open No. H8-97821; Japanese Patent Laid-Open No. 2001-189971). Specifically, a wireless communication system is known in which address information, relay information, and the like are added to communication data and transmitted to multiple addresses, and relay terminals relay the data in accordance with the address information, relay information, and the like.
Furthermore, a wireless communication scheme that aims to expand the communication range of a receiving terminal through plural senders transmitting identical data is known (Japanese Patent Laid-Open No. H11-122150). Specifically, a scheme is known in which plural transmission signals, to which have been added respectively differing amounts of delay, are transmitted from plural transmission terminals; on the receiving side, the received signal unaffected by interference is selected, equalization processing is performed thereon, and the original data is thereby estimated.
Furthermore, as technology for efficiently transmitting data wirelessly to a remote communication terminal, a scheme is known in which a relay terminal having a good condition of communication is selected and data is distributed to peripheral communication terminals by way of that relay terminal, thereby realizing efficient data transfer (Japanese Patent Laid-Open No. 2003-332977).
However, in recent years, where data communication functionality has become widespread, demand has increased for what is known as “real-time” communications, in which video data, audio data, and the like is transmitted from a data storage device through a communication line and is received and reproduced by a video display device, an audio reproduction device, or the like.
Schemes such as the abovementioned conventional schemes respond to the occurrence of disconnections and interruptions in the communication path caused by some kind of problem in the communication path by performing retransmission, changing paths, and so on. However, the retransmission processing, processing for changing paths, and so on are performed asynchronously, and thus transmission delay cannot be guaranteed. For this reason, when stream data that is temporally continuous, such as video or audio, is transmitted and continuously reproduced on the receiving side, and disconnections or interruptions occur in the communication path, there are situations where data underruns occur on the receiving side. Therefore, there is a problem that the reproduced video is unstable, the reproduced audio cuts out intermittently, and so on.
In the abovementioned conventional schemes, by using plural paths, reception can be carried out properly even if disconnections or interruptions occur in a single path. However, these processes assume predetermined plural transmission terminals and a single receiving terminal, and does nothing more than implement the connection of plural paths by eliminating signal interference from the plural transmission terminals. For this reason, when performing data transfers in unison to plural receiving terminals, such as with multi-channel stream data, mutual interference arises when data is transmitted to the respective receiving terminals over plural paths.